1873-1961

American Physicist

Lee De Forest introduced a third element into the diode vacuum tube designed by John Ambrose Flemming (1849-1945), providing a means by which a small voltage applied to this element could have a large effect on the current of electrons flowing between cathode and anode. The triode made possible the amplification of weak electrical signals, which in turn made possible the transmission of high quality audio and video signals by radio waves. The transistor, a solid-state device with the electrical properties of a triode, eventually replaced the vacuum tube triode in most applications.

De Forest had a somewhat unusual childhood. His father was a Congregationalist minister and President of the Talledega College for Negroes in Alabama. As a result, the white community ostracized his family, and Lee made his friends among the black children of the town. De Forest attended a...